Ground effect machines

ABSTRACT

A ground effect machine having a control system by means of which, when machine speed increases, the gap or daylight clearance at the front of the machine between the structure thereof and the surface along which the machine travels, is progressively reduced, so as to reduce the direct ramming inflow feed to the cushions by the dynamic pressure set up by the speed of the machine.

United States Patent [72] lnventors Jean Henri Bertin Neuilly-sur-Seine; Paul Francois Guienne, Paris; Francois Gilbert Park, Bayonne, all of, France [21] Appl. No. 864,685

[22] Filed Oct. 8,1969

[45] Patented Aug. 24, 1971 [73] Assignee Bertin & Cie

Piaisir, France [32] Priority Oct. 10, 1968 [33] France [54] GROUND EFFECT MACHINES 10 Claims, 7 Drawing Figs.

[52] US. Cl 104/23 FS, 104/23 R,104/134,180/122,180/126 [51] lnt.C1. B611) 13/08 [50] Field 01 Search 104/23, 23

[56] References Cited UNITED STATES PATENTS 3,190,235 6/1965 Bertin 1. 104/134 3,272,271 9/1966 Cockerell... 180/122 3,291,239 12/1966 Eggington 180/128 3,486,577 12/1969 Jackes 180/126 Primary ExaminerArthur L. La Point Assistant Examiner-D. W, Keen Attorney-Stevens, Davis, Miller & Mosher ABSTRACT: A ground effect machine having a control system by means of which, when machine speed increases, the gap or daylight clearance at the front of the machine between the structure thereof and the surface along which the machine travels, is progressively reduced, so as to reduce the direct ramming inflow feed to the cushions by the dynamic pressure set up by the speed of the machine.

1 8: 1/2 i q h Patented Aug. 24, 1971 4 Sheets-Sheet 1 Patented Aug. 24, 1971 3,601,052

4 Sheets-Sheet 2 Patented Aug. 24, 1971 4 Sheets-Sheet 5 4 Sheets-Sheet 4.

GROUND EFFECT MACHINES The present invention relates to ground effect craft or machines, i.e., craft or machines whose lift and possibly guidance are at least partly performed by pressure fluid cushions.

Cushions of the kind specified are fed with fluid at a pressure high enough for them to equilibrate the load applied to them, having regard to their dimensions. More particularly, cushions which at least provide lift for the machine equilibrate the weight thereof. However, at high speeds the dynamic forward pressure may exceed the cushion pressure required for the satisfactory operation of the machine, in which case the cushions are directly fed via the gap at the front of the machine lying between the structure thereof and/or the cushion-confining device, if any, and the surface along which the machine moves.

The present invention relates to a control system by means of which, when machine speed increases, the daylight clearance is gap at the front surface of the machine between the structure thereof and/or the cushion-confining devices, if any, which extend downwardly from the machine, and the surfaces along which the machine is lifted and guided, is progressively reduced, so as to reduce the direct feed to the cushions by the dynamic pressure set up by the speed of the machine. The term daylight clearance is well known in the art and signifies the gap between the lowest part of an air cushion vehicle and the surface when the vehicle is supported on its cushion which acts against such surface.

The presentinvention also relates to devices enabling the control function to be performed. According to a first embodimentof the invention, to confine a cushion over at least portion of its front surface, use is made of a mobile member formed, for instance, by a transverse plate which is articulated around an axis of its plane and whosefront surface is subjected to the dynamic forward pressure. Its rear surface is subjected to the pressure of the cushion and resilient return means acting on either side of a neutral position corresponding to zero stressing.

The mobile plate can be connected to a mechanical adjusting device, for instance, a jack.

The mobile plate can also be subjected to the action of a force set up by a negative pressure in a chamber advantageously connected via a conduit to a zone in which the static pressure is low. For instance, such chamber can be connected to the periphery of the outer fluid inlet conduit of the device feeding the cushions with pressurized fluid. The value of the static pressure can vary with the speed of the machine if, for instance, such inlet discharges towards the front of the machine.

According to another embodiment of the invention, to reduce progressively the gap at the front of a pressure fluid cushion, use is made of a nozzle directed towards the supporting surface and extending transversely and substantially over the whole cushion width, so that when the nozzle is fed with pressurized fluid it produces a curtain which reduces the flow section at the front of the cushion. Advantageously, the nozzle is directed towards the front of the machine in relation to the preferential direction of travel thereof. A plurality of orifices can be substituted for the nozzle, the orifices being close enough together to form a substantially continuous curtain.

Preferably, the gaseous fluid required for cushion operation is advantageously supplied via a fluid compressor driven by suitable means and interposed between an outer fluid inlet fed by the dynamic pressure and the cushions. Since the dynamic forward pressure varies with machine speed, cushion pressure is brought to its correct value either by the characteristics of the compressor and the feed circuit, or by any other automatic or nonautomatic means. For instance, the feed collectors of the cushions can have calibrated flaps allowing excess pressure fluid to escape to atmosphere. Alternatively, the machine can be so designed that as a result of its external aerodynamics a resulting force is directed towards the supporting surfaces of the machine. In this way the useful load of the machine is effectively increased when speed rises. The pressure in the cushions therefore also increases in relation to speed.

The invention will be clearly understood from the following description of a nonlimitative exemplary embodiment thereof, with reference to the accompanying drawings; details to be gathered both from the drawings and the description of course form part of the invention.

FIG. 1 is a diagrammatic elevation of a ground effect machine comprising improvements according to the invention and associated with a guide track.

FIG. 2 is an enlargement of a detail shown at 11 in FIG. 1.

FIG. 3 is a view similar to Fig. 2, showing a second embodiment of the invention.

FIGS. 4 and 5 are half views of a ground effect machine associated with a guide track and comprising improvements according to the invention.

FIG. 6 is a section, taken along the line VI-Vl in Fig. 4.

FIG. 7 is a section, taken along the line VII-VII in Fig. 5.

In the following description, only the machine's lift cushions comprise improvements according to the invention; clearly, such devices can also be applied to the cushions guiding the machine.

Fig. 1 shows a machine 2 cooperating with a guide track I of inverted T cross section. To feed cushions disposed on either side of central guide extension 13 of the track 1, the front of the machine has outer fluid pickups 3 which feed compressors 4 driven by a motor 5. The fluid leaving each of the compressors is directed into a duct 6 feeding, via branches 7, 8, at least one cushion bearing against the carrying portions 12 of the track 1, and at least one cushion bearing against the central extension 13 of the track 1.

At their downstream ends, the ducts 6 have flaps l0 kept closed by calibrated springs 100, the purpose of the flaps being to keep the pressure in the ducts 6 at the correct value.

The cushions are substantially rectangular in plan and bounded at their portion adjacent the structure of the machine by a partition 14, being bounded laterally and at the rear by I enclosures to be progressively reduced when the dynamic pressure due to speed exceeds the nominal value.

This device comprises an apron l7 articulated around a pivot 18 unitary with the partition 16 and prolonging the latter in the direction of the supporting surface; the apron 17 is subjected to the action of the forces due to the pressure of the cushion and the tension of a spring 19 on the one hand, and the action of the forces set up by the dynamic forward pressure on the other. A stop 21 limits the travel of the apron 17. A joint cover 22 advantageously provides sealing tightness in line with the articulation of the apron.

The device operates as follows:

When the machine moves, the apron -17 occupies a position such as that, for instance, shown in Fig. 2. Such position is determined on the one hand by the action of the force set up by the pressure of the cushion, which acts on the whole rear surface of the apron, and on the other hand by the dynamic forward pressure and the action of the spring 19. If, for instance, the external aerodynamics of the machine are such that a resulting force is directed towards the cushion-supporting surface when machine speed increases, cushion pressure also increases with speed. The force set up by cushion pressure on the apron 17 increases so that the flow section via which the enclosure containing the fluid cushion can be fed with fluid from outside by the dynamic forward pressure is progressively reduced. The force set up by such pressure also increases, but remains less than the force set up by cushion pressure, since the front surface of the apron 17 is exposed to the excess pressure resulting from the speed of. movement of the machine only over a very small proportion of the apron surface, since it is masked by the partition 16.

A mechanical device, such as a jack 23, can control the apron 17, more particularly if the partition 16 is eliminated. The jack can .be controlled by one or more operational parameters of the machine, such as, for instance speed, cushion pressure, by means of devices not shown, or else the jack can be controlled from the machine control panel.

The assembly made up by the apron 17 and the spring 19 can be replaced by a flexible strip which has the same displacement as the apron 17 and the same resilience as the spring 19 and is attached to the partition 16 without an articulation.

Fig. 3 shows a variant embodiment of the invention. A cushion 9 situated forward of the machine in relation to a preferential direction of movement thereof, has at its front an apron articulated around a pivot 26 which is substantially parallel with the surface along which the machine moves and extends through the center of the apron.

The apron has one end 25a having a friction joint 27 cooperating with the inside walls of a chamber 28. Stops 29, 30 limit the movements of the apron. A fluid pickup 31 connects the chamber 28 to the conduit 3a upstream of a compressor 4. When the machine moves, the apron is subjected to the action of the following forces:

That half of the apron cooperating with the chamber 28 is subjected on its front surface to the action of the forces set up by a static excess pressure due to the movement and on its rear surfaceto a negative pressure in the chamber 28 maintained by the fluid pickup 31 discharging into the conduit 3a, the value of such negative pressure varying with machine speed.

The other half of the apron 25 is subjected on its front surface to the action of the forces set up by the dynamic pressure due to the movement, and on its rear face to the pressure of the cushion 9 A sp'ring32, possibly associated with a shock absorber, is provided to make apron movements progressive. The spring operates by extension and tends to retain the apron 25 against the stop 29.

The device operates as follows:

During travel, the plate 25 takes up an intermediate position between the two stops 29, 30, for instance the position shown in the drawings. This arrangement is substantially independent of the pressure caused by the movement, since such pressure acts on the front surface of the plate 25 on either side of the pivot 26. in proportion as machine speed increases, there is a greater increase in speed at the lower portion of the apron 25, the'result being reduced excess pressure. The resultant of the forces therefore tends to move away from the pivot 26 in the direction of the end 25a of the apron 25, and this is favorable to the operation of the apparatus.

In proportion as machine speed increases, the negative pressure in the chamber 28 increases also the apron moves towards the stop 30, thus reducing the passage between its lower edge and the track. The feed to the cushion via the dynamic pressure entering the leakage gap is therefore reduced.

As a variant, the pressure pickup 31 might be disposed on the sides of the vehicle or in a zone where there is normal atmospheric pressure, more particularly if cushion pressure increases in relation to machine speed, as seen with relation to Fig. 2.

Figs. 4-6 and 7 illustrate other devices for the performance of the method according to the invention. These Figures show the front of a ground effect machine lifted and guided by pressure fluid cushions 35, 36 supported on a track 37. The

cushions 35, 36 are bounded laterally and at the rear by walls,

as 38, which are solid but which are capable of limited deformations, the cushions being bounded at the front by a wail 39. The free end 39a of the wall 39 comprises a nozzle 41 extending over substantially the whole length of the wall.

The nozzle 41 is adapted to deliver a flow directed towards the front of the machine in relation to the direction of movement thereof, and in the direction of the supporting surface. The nozzle 41 is fed with pressure fluid via one or more conduits 42 formed, for instance, in thethickness of the wall 39.

The or each conduit is connected to a pressure fluid source so that when they are supplied, the nozzle 41 delivers a fluid curtain directed towards the cushion supporting surface, thus reducing the gap via which the cushions run the risk of being supplied with fluid by the dynamic forward pressure, producing a constriction by a fluid diaphragm.

The pressure fluid source can be (Figs. 4 and 6) a dynamic pressure pickup 43 with which the wall 39 is formed and which is connected to the conduit 42 via a conduit 44 comprising a divergent portion 44a. The pressure pickup 43 advantageously extends over the whole width of a cushion with which it is associated. Alternatively, it could be either wider or narrower and/or combined with an extra device for producing pressure fluid, such as, for instance, a series of injectors disposed in the conduit 44.

The nozzle 41 can be fed by a compressor driven, for instance, by the same power source which either feeds pressure fluid to the cushions or propels the machine.

To reduce progressively the gap disposed at the front of the cushions, as shown in Fig. 7, an independent compressor 45 can be used controlled by the speed of movement of the machine, via the agency of a suitable device, such as that shown in Fig. 7. The compressor 45 is driven by an electric motor 46 whose supply circuit has a device 47 for adjusting the strength of the current supplied by a source 48.

The device 46 can be formed by a rheostat whose slider 49 is actuated by a piston 51 subjected to the dynamic forward pressure of the machine on one of the piston faces 51a and to the opposing action of a spring on its other face. Conduits, as 53, for connection to atmosphere enable the piston to slide in its housing 54.

The position of the piston 51 inside its housing 54 adjusts the position of the cursor 49 connected to one of the terminals of the source 48. In proportion as the machine moves more rapidly, the piston 51 compresses the spring to a greater extent, the result being an increase in the strength of the current supplied to the motor 46 and therefore in its speed.

The gap at the front of the cushions is thus progressively reduced by the fluid curtain delivered by the nozzle 41, as the speed of movement of the machine increases.

The scope of the invention would not be exceeded if the nozzle 41 were replaced by a plurality of orifices close enough together to form a substantially continuous curtain, or if a succession of curtains were to be disposed one after the other substantially parallel with one another.

Clearly, these embodiments have been given merely by way of example and could be modified, inter alia by the use of technical equivalents, without exceeding the scope of the invention.

We claim:

1. A cushion pressure control process for a high-speed ground effect machine having a cushion space which communicates with the ambient medium ahead of said machine through a frontally extending, controllable daylight clearance of variable effective gap width, said process comprising the steps of sensing the forward speed of said machine, and reducing said variable effective gap width as said speed increases thereby hindering ramming inflow of ambient medium through said daylight clearance and into said cushion space.

2. In a high-speed ground effect machine having a cushion space which communicates with the ambient medium ahead of said machine through the effective gap width of a frontally extending daylight clearance, a cushion pressure control system comprising means sensing the forward speed of said machine, daylight clearance control means for varying said effective gap width, and means interrelating said speed sensing means and said daylight clearance control means to reduce said effective gap width upon increase of said speed thereby hindering ramming inflow of ambient medium through said daylight clearance and into said cushion space.

3. Control system as claimed in claim 2, wherein said daylight clearance control means comprise a frontally extending, movable wall member frontally bounding said cushion space and having an adjustably positionable free edge defining a variable effective gap width of said daylight clearance, an inner surface exposed to cushion pressure which urges said movable wall member in a direction to decrease said variable effective gap width, and an outer surface exposed to ambient dynamic pressure which urges said movable wall member in the opposite direction to increase said variable effective gap width; and means borne by said machine for countering the action of said dynamic pressure on said movable wall member.

4. Control system as claimed in claim 3, wherein said dynamic pressure countering means comprises screen means shielding partly said movable wall member from said dynamic pressure.

5. Control system as claimed in claim 3, wherein said dynamic pressure countering means comprises pressure operated servomotor means adapted to urge said movable wall member in said former mentioned direction to decrease said variable effective gap width.

-6. Control system as claimed in claim 5, wherein said movable wall member comprises a hinged flap, and said servomotor means comprise a pneumatic chamber under negative pressure, and a pressure-responsive partition fast with said hinged flap and extending the same beyond the hinge thereof, said partition being exposed to said negative pressure.

7. Control system as claimed in claim 2, wherein said daylight clearance control means comprises frontally extending variable-supply nozzle means for forming an adjustable fluid curtain frontally bounding said cushion spaced and defining an effective gap width which varies in accordance with the supply of said variable-supply nozzle means, and wherein said interrelating means comprises variable pressure fluid supply means under the control of said speed-sensing means for delivering to said nozzle means a pressure fluid supply flow which increases as said speed increases.

8. Control system as claimed in claim 7, wherein said speedsensing means comprises a forwardly facing, air intake, and wherein said variable-pressure fluid supply means comprises a difiuser interposed between said air intake and said nozzle means.

9. Control system as claimed in claim 7, wherein said variable-pressure fluid supply means comprises a compressor discharging into said nozzle means, and electric motor driving said compressor, and means for varying the energization of said electric motor, said energization varying means being under the control of said speed sensing means.

10. Control system as claimed in claim 9, wherein said energization-varying means comprises a rheostat with a resistance control slide, and wherein said speed-sensing means comprises a dynamic pressure sensitive-member and a control linkage between said member and said slide. 

1. A cushion pressure control process for a high-speed ground effect machine having a cushion space which communicates with the ambient medium ahead of said machine through a frontally extending, controllable daylight clearance of variable effective gap width, said process comprising the steps of sensing the forward speed of said machine, and reducing said variable effective gap width as said speed increases thereby hindering ramming inflow of ambient medium through said daylight clearance and into said cushion space.
 2. In a high-speed ground effect machine having a cushion space which communicates with the ambient medium ahead of said machine through the effective gap width of a frontally extending daylight clearance, a cushion pressure control system comprising means sensing the forward speed of said machine, daylight clearance control means for varying said effective gap width, and means interrelating said speed sensing means and said daylight clearance control means to reduce said effective gap width upon increase of said speed thereby hindering ramming inflow of ambient medium through said daylight clearance and into said cushion space.
 3. Control system as claimed in claim 2, wherein said daylight clearance control means comprise : a frontally extending, movable wall member frontally bounding said cushion space and having an adjustably positionable free edge defining a variable effective gap width of said daylight clearance, an inner surface exposed to cushion pressure which urges said movable wall member in a direction to decrease said variable effective gap width, and an outer surface exposed to ambient dynamic pressure which urges said movable wall member in the opposite direction to increase said variable effective gap width; and means borne by said machine for countering the action of said dynamic pressure on said movable wall member.
 4. Control system as claimed in claim 3, wherein said dynamic pressure countering means comprises screen means shielding partly said movable wall member from said dynamic pressure.
 5. Control system as claimed in claim 3, wherein said dynamic pressure countering means comprises pressure-operated servomotor means adapted to urge said movable wall member in said former mentioned direction to decrease said variable effective gap width.
 6. Control system as claimed in claim 5, wherein said movable wall member comprises a hinged flap, and said servomotor means comprise a pneumatic chamber under negative pressure, and a pressure-responsive partition fast with said hinged flap and extending the same beyond the hinge thereof, said partition being exposed to said negative pressure.
 7. Control system as claimed in claim 2, wherein said daylight clearance control means comprises frontally extending variable-supply nozzle means for forming an adjustable fluid curtain frontally bounding said cushion spaced and defining an effective gap width which varies in accordance with the supply of said variable-supply nozzle means, and wherein said interrelating means comprises variable pressure fluid supply means under the control of said speed-sensing means for delivering to said nozzle means a pressure fluid supply flow which increases as said speed increases.
 8. Control system as claimed in claim 7, wherein said speed-sensing means comprises a forwardly facing, air intake, and wherein said variable-pressure fluid supply means comprises a diffuser interposed between said air intake and said nozzle means.
 9. Control system as claimed in claim 7, wherein said variable-pressure fluid supply means compriSes a compressor discharging into said nozzle means, and electric motor driving said compressor, and means for varying the energization of said electric motor, said energization varying means being under the control of said speed sensing means.
 10. Control system as claimed in claim 9, wherein said energization-varying means comprises a rheostat with a resistance control slide, and wherein said speed-sensing means comprises a dynamic pressure sensitive member and a control linkage between said member and said slide. 